The present invention relates to electric toothbrushes, more particularly this invention is an improvement in the structure of a vibratory electric toothbrush whose head can vibrate laterally with respect to the longitudinal axis of the toothbrush.
The benefit of using an electrically operated toothbrush to clean one""s teeth is well known and has resulted in many innovations for electric toothbrushes. However, there have been not many innovations that are related to vibratory electric toothbrushes. A vibratory electric toothbrush generally comprises an electric motor, a mechanism that translates the motor movement into lateral vibratory movement, a toothbrush head mounted with plurality of bristles which deliver the vibratory movement onto user""s teeth, a battery source, and a holder that holds all parts in a workable condition. When such a vibratory electric toothbrush is operated in a daily tooth cleaning, the toothbrush head and the bristles vibrate laterally with respect to the longitudinal axis of the toothbrush and moves approximately in a plane parallel to the tooth surface. Since the vibratory movement in the bristles can be adapted to the up-and-down movement along tooth gaps by a user holding the toothbrush horizontally in the tooth cleaning, this kind of electric toothbrush has an advantage of effectively cleaning in tooth gaps as well as cleaning the tooth surfaces with minimum hurting to the gums between user""s teeth.
U.S. Pat. No. 2,439,262 for a Power-Operated Mechanism discloses a hand manipulable device applicable to a vibratory electric toothbrush having a motion translating mechanism that translates rotary movement into rocking movement. The motion translating mechanism generally comprises a handle, a drive pin within the handle eccentrically extended to a driven shaft which is rotated by an external source during its operation, and a rock arm, pivotally attached in one end of the handle by a spheroidal bearing, having a working end portion projecting beyond the end of the handle to drive an applicable head and having a head at the other end provided with a transverse slot which receives the drive pin. When the mechanism is operated, the drive pin circulates and slides in the slot of the rock arm head and causes rocking movement in the arm. To restrict the rock arm to move in a plane, two spaced-apart guiding walls are provided for the rock arm. The mechanism is substantially simple in structure for translating the rotary movement into the rocking movement, but it is not sufficiently energy efficient since the mechanism employs the guiding walls and the spheroidal bearing that require several substantial contacts between static parts and moving parts which cause an additional energy loss due to the friction while the mechanism is operated. Hence it is not suitable for a portable electric toothbrush powered by a battery that needs better energy efficiency.
U.S. Pat. No. 5,365,627 for a Stem Brush With Automatic Insertion System discloses a joint structure of a handle and a stem brush connection for an oral hygiene device. The structure generally comprises a pair of keys on a motor driven shaft in a handle, a radially extending flange on the base of the shaft, and a receiving portion in a stem brush which comprises a bore to receive the shaft, slots to receive the keys, a pair of ramping sleeves to guide the keys into the slots, and a pair of flexible arms having a recess to receive the flange on the base of the shaft. Although the system has an advantage of easy connection of the handle to the stem brush, it has a drawback of a gap left between the handle and the stem brush, which allows fluids to leak into the handle that degrades its hygienic function since bacteria may grow inside the handle.
One object of the present invention is to provide an improved electric toothbrush powered by battery that can generate lateral vibratory movement in the toothbrush head with respect to the longitudinal axis of the toothbrush. The mechanism generally comprises a toothbrush head and a swing arm pivotally attached in the forward end of a sleeve whose other end is longitudinally attached to a toothbrush handle. The swing arm comprises a tail portion and a head portion and an elongated middle portion intermediate the tail portion and the head portion. The tail portion of the swing arm has a transverse groove with an elongated opening to receive a drive head mounted eccentrically to the motor shaft aligned within the toothbrush handle; and the head portion extending to the toothbrush head has a transverse bore penetrating therein to receive a pivotal pin for the pivotal attachment of the swing arm to the forward end of the sleeve. As an electric toothbrush with this structure is operated, the drive head circulates in a plane approximately perpendicular to the axis of the motor shaft and slides in the transverse groove of the swing arm; and the drive head is able to slide freely in the transverse groove in the lengthwise direction of the transverse groove opening without causing the swing arm to move, but pushes back and forth within the transverse groove in the other direction perpendicular to the first said direction, which causes the swing arm and the toothbrush head to vibrate laterally or to swing with the pivot pin as a fulcrum.
Another object of the invention is to provide an electric toothbrush that is simple in construction and effective in transforming electric energy into useful vibratory movement in the toothbrush head. The structure of the head portion of the swing arm in the present invention is invented for two major working characteristics: first, the head portion of the swing arm is bent from the longitudinal axis thereof to cause the toothbrush head to be inclined from the longitudinal axis of the swing arm, which is desirable in cleaning user""s back teeth; secondly, there is a lateral prominent point portion on the lower part of the head portion, distal from the toothbrush head. This prominent point portion is in contact with the inner wall proximal thereto in the forward end of the sleeve when a user presses the bristles in the toothbrush head against teeth as in a daily tooth cleaning. The contact helps to dissipate the force generated by the user""s pressing of the bristles against teeth with minimum impact on the motor power.
Still another object of the invention is to provide an electric toothbrush having a toothbrush head that is attachable, secured, and sealed to a drive portion. The toothbrush head in this invention is attachable to the drive portion and is secured by a flexible collar member. The toothbrush head has a base portion mounted with plurality of bristles and a neck portion extended downward to the base portion. A recess with an opening at the free end of the neck portion is provided within the toothbrush head to receive an extension in the head portion of the swing arm. An annular recess is transversely positioned on the neck portion to receive an annular inward projection in the collar member for the secured attachment of the toothbrush head to the drive portion. The collar member also serves as a waterproof means to prevent liquids from leaking into the drive portion by covering the joint gap between the toothbrush head and the end of the drive portion adjoining the toothbrush head.